There is well known a heat-sensitive recording material which is so designed as to produce a record image by the aid of a color reaction that takes place between a colorless or light-colored basic dye and an organic or inorganic color developer when the two substances are brought into contact with each other by heat. A heat-sensitive recording material of this type is comparatively inexpensive and suitable for use on a compact recording machine, which is relatively easy in its maintenance. And it is used as a recording medium in facsimile system or various computer systems or in other systems. For said recording material, it is often required to have more improved resistances to oils or plasticizers upon its application area. To meet such requirements, there have been developed relevant basic dyes and color developers. However, many of such color developers, though they exhibit a good chromogenic performance, cannot be directly applied to a substrate for a heat-sensitive recording material as they are, because of their pronounced tendency of generating foreign matters to contaminate the recording head. In order to solve this problem, there has been proposed to use such color developer in combination with a proper pigment. This proposal is effective in solving the above problem. However, under this proposal, there will often occur another problem that the whiteness of the recording layer of a heat-sensitive recording material is remarkably reduced. For example, in the case where a highly oil-absorbing pigment represented by an anhydrous silica fine powder is used, the resulting heat-sensitive recording material will be such that does not cause the problem of contaminating the recording head with foreign matters but does a remarkable reduction in the whiteness of the recording layer. And in the case where an ordinary precipitated calcium carbonate is used as the pigment, occurrence of the reduction in the whiteness of the resulting recording layer is effectively prevented but the resulting recording material will be such that is apt to generate foreign matters to contaminate the recording head when it is used as the recording medium in facsimile system or the printer used in computer system.
Under these circumstances, there is a demand for provision of an improved heat-sensitive recording material which does not cause any foreign matter to contaminate the recording head and which is not deteriorated with the original whiteness even upon storage for a long period of time.